﻿358 
  Messrs. 
  De 
  La 
  Rue, 
  Muller, 
  and 
  Spottiswoode 
  on 
  [Apr. 
  8, 
  

  

  the 
  latter 
  showing 
  some 
  curious 
  phenomena 
  with 
  a 
  hydrogen 
  residual 
  

   vacuum, 
  which 
  will 
  be 
  described 
  in 
  a 
  future 
  paper. 
  A 
  tube 
  which 
  has 
  

   given 
  the 
  most 
  striking 
  results 
  is 
  8 
  inches 
  (20*32 
  centims.) 
  long, 
  and 
  has 
  

   a 
  series 
  of 
  six 
  aluminium 
  rings 
  varying 
  in 
  diameter 
  from 
  § 
  of 
  an 
  inch 
  to 
  

   about 
  1| 
  of 
  an 
  inch 
  (0*95 
  to 
  3*17 
  centims.), 
  the 
  thickness 
  of 
  the 
  wire 
  

   being 
  about 
  (0*16 
  centim.) 
  of 
  an 
  inch 
  ; 
  the 
  rings 
  are 
  a 
  little 
  more 
  than 
  

   1 
  inch 
  (2*54 
  centims.) 
  apart 
  ; 
  and 
  connecting 
  wires 
  of 
  platinum 
  pass 
  

   through 
  the 
  tube 
  from 
  each 
  ring 
  and 
  permit 
  of 
  the 
  length 
  and 
  other 
  condi- 
  

   tions 
  of 
  the 
  discharge 
  being 
  varied. 
  

  

  At 
  times 
  the 
  terminals 
  of 
  the 
  battery 
  were 
  placed 
  in 
  connexion 
  with 
  

   accumulators 
  of 
  different 
  kinds 
  — 
  for 
  instance, 
  two 
  spheres 
  of 
  18 
  inches 
  

   (45*72 
  centims.) 
  in 
  diameter, 
  presenting 
  each 
  a 
  superficies 
  of 
  7*07 
  square 
  

   feet 
  (65*68 
  square 
  decims.), 
  and 
  cylinders 
  of 
  paper 
  covered 
  with 
  tinfoil, 
  

   each 
  having 
  a 
  surface 
  of 
  16 
  square 
  feet 
  (148*64 
  square 
  decims.) 
  ; 
  the 
  

   globe 
  and 
  cylinders 
  were 
  in 
  all 
  cases 
  carefully 
  insulated. 
  Other 
  accumu- 
  

   lators 
  were 
  composed 
  of 
  coils 
  of 
  two 
  copper 
  wires 
  y 
  1 
  ^ 
  of 
  an 
  inch 
  

   (0*16 
  centim.) 
  in 
  diameter, 
  covered 
  with 
  gutta 
  percha, 
  in 
  two 
  folds, 
  ^ 
  

   of 
  an 
  inch 
  (0*08 
  centim.) 
  thick. 
  One 
  coil 
  contains 
  two 
  wires, 
  A 
  A 
  and 
  

   B 
  B' 
  (fig. 
  1), 
  coiled 
  side 
  by 
  side, 
  each 
  being 
  174 
  yards 
  (159 
  metres) 
  long, 
  

   another 
  with 
  two 
  wires 
  each 
  350 
  yards 
  (320 
  metres) 
  long 
  ; 
  of 
  the 
  latter 
  

   we 
  have 
  two 
  coils. 
  

  

  Fig. 
  1. 
  

  

  In 
  addition 
  to 
  these 
  accumulators 
  we 
  have 
  several 
  others 
  formed 
  of 
  

   alternate 
  plates 
  of 
  tinfoil 
  and 
  insulating 
  material, 
  such 
  as 
  paper 
  satu- 
  

   rated 
  with 
  paraffine, 
  and 
  also 
  sheets 
  of 
  vulcanite. 
  These 
  are 
  of 
  various 
  

   capacities 
  and 
  contain 
  from 
  5 
  to 
  several 
  hundred 
  square 
  feet. 
  The 
  largest 
  

   has 
  a 
  capacity 
  of 
  47*5 
  microfarads 
  ; 
  when 
  it 
  is 
  discharged 
  it 
  gives 
  a 
  very 
  

   bright 
  short 
  spark, 
  accompanied 
  by 
  a 
  loud 
  snap 
  ; 
  the 
  charge 
  deflagrates 
  

   8 
  inches 
  (20*32 
  centims.) 
  of 
  platinum 
  wire, 
  *005 
  inch 
  (0*127 
  millim.) 
  in 
  

   diameter, 
  when 
  it 
  is 
  caused 
  to 
  passed 
  through 
  it. 
  Each 
  accumulator 
  

   gives 
  different 
  results 
  ; 
  but 
  for 
  the 
  present 
  we 
  shall 
  confine 
  ourselves 
  to 
  

   a 
  description 
  of 
  the 
  experiments 
  made 
  with 
  the 
  coil-accumulators. 
  

  

  "When 
  the 
  terminals 
  of 
  the 
  battery 
  are 
  connected 
  with 
  the 
  wires 
  of 
  a 
  

   vacuum-tube 
  which 
  permits 
  of 
  the 
  passage 
  of 
  the 
  current, 
  the 
  wires 
  

   (especially 
  that 
  connected 
  with 
  the 
  zinc 
  end) 
  become 
  surrounded 
  with 
  a 
  

   soft 
  nebulous 
  light, 
  in 
  which 
  several 
  concentric 
  layers 
  of 
  different 
  degrees 
  

   of 
  brilliancy 
  are 
  seen 
  ; 
  in 
  most 
  cases 
  there 
  is 
  either 
  no 
  indication 
  of 
  stra- 
  

   tification, 
  or 
  only 
  a 
  feeble 
  ill- 
  defined 
  tendency 
  to 
  stratification 
  : 
  the 
  tubes 
  

  

  